The latest incident happened around 7:05 a.m. in the 800 block of Peakwood Drive near Red Oak Drive.

Officials said a bus was stopped for loading and unloading passengers when another Metro bus turned right onto Peakwood from Red Oak and hit the woman. She had been attempting to cross the street behind the bus she had just exited.

It was not immediately known whether Martinez was trying to pass the other bus, or whether he'd stopped at the stop sign on Red Oak before turning.

Drivers are allowed to pass another bus if they're following safe procedures, said Metro spokeswoman Tracy Jackson.

Another passenger on the first bus said she had just gotten off it with her son when she saw the second bus hit the woman in the street. The passenger, who declined to be identified but shared her account with police, said the driver of the second bus was speeding to get around the parked bus.

"She didn't run toward that bus; he ran her over," the witness said.

She yelled to say the driver hit a woman, and he stopped, saying he was running behind on his route, the woman said.

The witness pointed to several schools and daycare centers nearby and said the bus could have realistically hit a child.

"The street is dark all day every day, and there's no reason you should be on the opposite side of the street, speeding through here," the woman said. "Kids come through here all times of the day, walking."

The woman died at the scene, Jackson said. As of Wednesday evening, she had not been identified.

Metro police are investigating.

"Just because he is a Metro employee doesn't mean he is going to be treated any differently," Jackson said.

Prosecutors made the decision to charge Martinez, Jackson said, without police making a recommendation.

Both of the prior crashes occurred when the pedestrians were in crosswalks, including the last in January 2017 when a driver did not see Kenneth Unfried crossing the street and struck him in downtown Houston. Officials acknowledged after that crash that the collision was avoidable.

In September, Metro reported 47 crashes involving buses, below its stated monthly goal of 52. Thirteen of those were deemed preventable, meaning the bus operator could have taken an action to avoid the crash.

Lately, Metro's safety efforts have focused more on the light rail system, which has had five fatalities in the past year, including one in early October.

Transit officials have also faced scrutiny from riders, who have complained about the behavior of some bus operators. Riders have detailed drivers who declined to lower ramps from elderly passengers and operators that were combative or dismissive of some riders.

Metro CEO Tom Lambert said at the agency's Oct. 25 meeting that the issue is isolated to a few operators. Of Metro's 1,630 operators, 52 of them -- or 3 percent -- received seven or more complaints in the past year. Across the transit system, drivers average 1.2 complaints annually.

"We are committed to retraining," Lambert said of the drivers with high numbers of complaints. "We are going to be very up front with that. And if they do not improve then we will help them find somewhere to go if they do not need to be a part of Metro."

Metro spokespeople said the organization will determine Martinez's employment status at the end of an investigation and that he's "not operating a bus right now." Metro didn't clarify when asked whether that means he won't be operating a bus until the conclusion of an investigation.

Transit officials are also looking into whether Martinez has been the subject of any other complaints by riders, and whether any of their other bus drivers have ever been charged in a crash.